It probally is humidity. Use a ratio of vermiculite to water of 1:1. Weight the eggs and watch for weight gain. You keeping the eggs the same side up as they were laid? Raise the temp a bit from 75 to between 80-85.
-----
Center for Reptile and Amphibian Conservation

Reptiles

1.0 Uroplatus phantasticus
2.0 Uromastyx malienisis
0.2 Eublepharis macularis
1.0 Chrysemys picta dorsalis
0.1 Physignathus cocincinus
0.0.1 Hemidactylus turcicus
0.1 Lepidactlyus lugrubis